Noise Outside DNL 65
10.05.2009 | Mary Ellen Eagan |
Well, this is a blog post I’ve been thinking about for some time (probably since before I knew what a “blog” was – though I just learned that the term was coined in 1984 – ironically, the same year I started in this business), but is precipitated by the publication of ACRP Synthesis 16, Compilation of Noise Programs in Areas Outside the DNL 65, primary author, yours truly.
If you’ve been tracking my publications closely (or reading Airport Noise Report), you’ll already know the conclusions. For those of you haven’t, I’ll summarize briefly.
The ACRP synthesis was based on an online survey of 43 airports, designed primarily to identify the airports’ reasons for addressing noise outside DNL 65, and the wide range of techniques used to address it. The survey included five general questions regarding noise issues outside DNL 65. I was not surprised by the results:
- A majority of respondents (83%) indicated that noise issues outside DNL 65 were “important,” “very important” or “critical” to their airport. The remaining 17% were evenly split, stating that noise issues outside the DNL 65 were “somewhat important” or “not at all important.”
How important are noise concerns outside DNL 65 for your airport?
- The most frequently listed method of minimizing noise outside the DNL 65 was operator education and outreach (74% of respondents), followed by noise abatement flight tracks (69%), preferential runway use programs (66%), noise abatement departure or arrival procedures (60%), and ground noise control (51%).
- Eighty percent of respondents indicated that “community concerns” were the motivation for addressing noise outside the DNL 65; fifty-seven percent also indicated that “preventative planning” was a motivation.
- Almost three-quarters of respondents (74%) indicated that more than 75% of their airport’s noise complaints came from people who live outside DNL 65.
- The most common outreach tools to communicate with people exposed to noise outside DNL 65 are websites (74%), community meetings/forums (74%), online tracking (40%), and newsletters (40%).
The survey also found the following:
- A majority of surveyed airports use noise abatement departure (63%) and arrival (51%) flight tracks and departure (54%) and arrival (40%) cockpit procedures to minimize noise over residential and other noise-sensitive neighborhoods. However, among surveyed airports there is no consistency in methodology among airports for evaluating noise abatement outside DNL 65, and there is little guidance or support from the FAA on appropriate metrics or criteria for evaluating noise abatement procedures.
- Most airports reported some procedures to minimize ground noise (69%); 25% of those airports reported that the procedures were developed primarily to address noise outside DNL 65, and an additional 38% reported that procedures were developed to address noise issues both inside and outside DNL 65.
- More than half of the surveyed airports (57%) reported having land use compatibility measures that apply outside DNL 65. The tools used by airports for land use compatibility planning include zoning, building permits that require sound insulation or residential and noise-sensitive non residential land uses, and disclosure to residents.
- The majority of respondents (58%) do not provide sound insulation to homeowners living outside DNL 65. However, 20% provide sound insulation for homes in contiguous neighborhoods (“block rounding”), and an additional 15% provide sound insulation for homes within the DNL 60 dB contour.
- Nearly three-quarters of respondents (74%) reported that they use both websites and face to face meetings to communicate with people exposed to noise outside DNL 65.
- The responding airports communicate with pilots about noise outside DNL 65 in a number of ways. The most common are: pilot briefings (40%) and Jeppesen inserts (40%), posters and handouts (37%), and FAA standards (17%); other methods include airfield signage, Airport Facility Directory Special Notices, videos distributed through flight schools, and phone calls.
What does it mean?
As I said above, none of these findings surprise me – and for those of you who work around airports, you’ll probably feel validated. The real question is what does it mean for public policy? I will be talking about results of this survey twice in the next couple of weeks: first at the AAAE Airport Noise Mitigation Symposiumin Boca Raton, FL on October 6th, and the following week (October 11) at the ACI-NA Environmental Affairs Committee Seminar in Austin, TX. I look forward to engaging discussion with you, and will try to post the highlights here for those of you that can’t join us.